What causes blood in the stool


The presence of blood in the stool tends to be frightening. If the cause is most often benign, you should always consult your doctor, the self-diagnosis being very dangerous. Indeed, it may be a disease for which the management must be immediate. However, the amount of blood found does not correlate with the severity of the problem.

The presence of blood in the stool may cause concern. This symptom is however most often benign in a young subject. The risk of a serious pathology, such as colorectal cancer, indeed increases with age, and according to family history. To watch, therefore.

While the presence of blood in the stool is a symptom that should not be overlooked and which requires medical attention, it can have many causes.

What causes blood in the stool

Blood in a child’s stool

Bleeding in the stools may appear in children following gastroenteritis or an episode of constipation . “These bleeds seem worrying for parents, but, in the absence of a history or associated symptoms, they are in reality harmless, and disappear quickly” , 

Bleeding in the stool in adults before age 50

Before age 50, bleeding in the stool is most often the result of hemorrhoidal disease or anal fissure . “In young people with no family history of colorectal cancer, bleeding in the stool is not an emergency, but justifies a diagnosis, and therefore a consultation with his doctor,” 

  • The hemorrhoids are vascular formations located in the anus. When they come out, bleed or cause pain, it is called hemorrhoidal disease. It is by far the most common cause of blood in the stool. It is treated with medical treatment against constipation and venotonics, possibly an ointment or suppositories.
  • The anal fissure is a tear in the skin over the anus. It manifests itself by bleeding and burning-type pain of varying intensity during and following defecation. Uncomfortable but benign, anal fissure is treated by prescription of constipation drugs (laxatives) and painkillers.

Blood in the stool during pregnancy

Pregnant women are more prone to hemorrhoidal diseases, and, to a lesser extent, anal fissures, pregnancy, and childbirth being triggers. Both are manifested in particular by blood in the stool. To relieve these inconveniences, talk to your doctor, he will prescribe an appropriate treatment.

Blood in the stool in adults after 50 years

From the age of 50, the probability of developing more serious pathologies, such as a polyp or colorectal cancer, increases. 95% of colorectal cancer cases occur after this age.

“A person who has or was prone to hemorrhoids when they were young might have a tendency to attribute to them the presence of blood in the stool. However, as we get older, there is a greater risk that this bleeding is a symptom of another more serious pathology, ” 

When visible bleeding in the stool occurs, it is, therefore, advisable to consult without delay. ” The colonoscopy is an examination admittedly binding, but must to determine the cause of bleeding,”

What causes blood in the stool: THE DIFFERENT CAUSES OF BLOOD IN THE STOOL

According to various studies, the blood in the stool comes in 95% of cases, from bleeding from the colon, rectum or anus. However, it can also have very diverse origins.


As the primary cause of blood in the stool, hemorrhoids remain the most justified explanation. In this case, the bleeding of a bright red color may sometimes be profuse after a bowel movement, but it disappears after a few minutes. Here are other important causes of this ailment:

  • Anal fissure: it is common in cases of intestinal transit disorders and causes minimal rectal bleeding. You may feel pain when passing stool;
  • The scratching lesions of anal dermatoses: these are yeast infection, contact eczema, or psoriasis. They generate red bleeding from the anus with low abundance;
  • Ulcerations of the rectum by trauma: blood in the stool can also be the cause of repeated rectal temperature measurements. In this case, the bleeding occurs right after using the thermometer;
  • Tumors of the anus, rectum, and colon: benign (polyps) or malignant (colorectal cancer), these tumors can cause bleeding, sometimes invisible to the eye;
  • Diverticulosis of the colon: it is an anatomical anomaly acquired from the colon and which is characterized by the presence of colonic diverticula;
  • Inflammation of the colon or rectum: these include chronic inflammatory bowel disease, infectious damage to the rectum through infection, acute infectious diarrhea, ischemic colitis in the elderly, etc. ;
  • Colonic angiodysplasias: they represent vascular malformations in the colon, especially in the elderly, which can lead to bleeding lesions;
  • Causes secondary to treatments: blood in the stool can also result from certain treatments such as pelvic radiotherapy, anticoagulant or anti-inflammatory treatment, use of ointments, an act of digestive surgery.


In addition to the origins already mentioned, rectal bleeding also has other secondary sources. When the bleeding involves, for example, the colonic or rectal area, the following are the possible causes:

  • A polyp or cancer of the anus, rectum or colon;
  • Colitis or inflammatory disease (Crohn’s disease);
  • Angiodysplasia (fragile and abnormal blood vessels can cause bleeding);
  • A peptic ulcer (the ailment comes from an open sore in the wall of the stomach or duodenum);
  • Long-term or high-dose use of anti-inflammatory drugs (aspirin, ibuprofen, naproxen);
  • Polyps (benign growths that can grow, bleed, and become cancerous );
  • Esophageal problems (tears in the esophagus can cause severe blood loss).

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